EP 2 024 147 B1 discloses an electric shaver comprising a housing, an electric motor mounted in the housing and comprising a drive shaft having a first rotary axis, a drive pin connected to the drive shaft eccentrically with respect to the rotary axis, and at least one driven shaft mounted in the housing for performing a movement relative to the housing. The driven shaft is indirectly coupled to the drive shaft by means of a gear mechanism converting a rotary motion of the drive shaft into a reciprocating motion of the driven shaft. The driven shaft is coupled to a cutter element of the shaver. The gear mechanism comprises a swing bridge. A further electric shaver comprising such a gear mechanism with a swing bridge is known e.g. from U.S. Pat. No. 4,167,060.
Further dry shavers are provided with a motor in a body portion of the housing, a drive-train arranged in the body and drive pins arranged relative to the body combined with a shaver head that is flexibly connected to the body. Typically the transfer of the rotation of the eccentric drive pin of the motor into a lateral or linear movement is realized via a so called “oscillating bridge”, a combination of a four bar joint mechanism with a groove where the eccentric of the motor is rotating in. The oscillating bridge transfers rotation into linear oscillation, transmits the mechanical energy of the motor to the head with the cutting elements and provides a spring load to the drive system that improves the energy balance of the dynamic system. Relative movements of the head towards the components arranged in the body and angled head to body arrangements may cause restrictions for the efficient and effective flow of forces from the motor to the head and the cutting elements. Further, this may cause unwanted friction, noise, wear and tear, technical complexity which comes along with cost and installation space requirements resulting in a bulky head design. At the same time these type of drive systems tend to be soft in their mechanical power transmission properties, e.g. the output value of deflection divided through the input value of deflection results in values lower 0.9 (effectiveness<0.9). The value for effectiveness in known solutions is significantly affected by the product architecture of a shaver, and there in particular via the inclination of the head towards the body.
As angled product architectures make the power flow go around the corner, the known solutions either connect the motor with the head, which results in bulky and misbalanced heads, or implement the motor in an inclined position relative to the body, which results in bulky bodies or complicated inner product architecture, or the inclination is compensated in an oscillating bridge, which typically results in a bulky handle or in reduced effectiveness of the transmission.
It is an object of the present disclosure to provide an electrically driven device permitting more flexibility regarding the design of the device. It is a further object to provide a device with a high dynamical stiffness of the gear mechanism.